Conventionally, methods have been considered to improve substantial transmission speed in consideration of communication efficiency i.e. total throughput of the system and occurrence of reception error. For example, such a scheme is proposed that communication parameters such as a modulation scheme, channel coding rate, error correcting coding scheme, spreading factor, the number of multiplexed codes, transmission power, etc. are adaptively selected based on an indicator indicating propagation path conditions and reception quality such as, for example, received signal power and SINR (Signal to Interference plus Noise power Ratio) (Non-patent Document 1). Particularly, the scheme for adaptively selecting modulation parameters such as a modulation scheme, channel coding rate, etc. is called the adaptive modulation scheme.
Further, following schemes have been considered in a communication system comprised of a base station apparatus and a plurality of communication terminal apparatuses where multicarrier communication is used in communications (downlink) from the base station apparatus to the communication terminal apparatuses (Non-patent Documents 2 and 3):
(1) scheduling for allocating a channel to each communication terminal apparatus is performed corresponding to reception quality of each channel in a downlink signal of each communication terminal apparatus; and
(2) further, adaptive modulation is performed in the downlink for each channel comprised of a single subcarrier or some subcarriers.
In addition, in the communication system that adopts scheduling and adaptive modulation scheme based on the reception quality of the communication terminal apparatus, in order to determine allocation and modulation parameters, it is necessary to notify the communicating party of an indicator such as received signal power and SINR of a channel used in communications indicating propagation path conditions and reception quality.
In the above-mentioned system, each communication terminal apparatus is required to notify the base station apparatus of reception quality information concerning each channel using an uplink control channel and the like. Therefore, there is a problem that the information amount of reception quality information transmitted on uplink becomes enormous in proportion to the number of communication terminal apparatuses and the number of channels. Then, to improve the aforementioned problem, techniques are proposed for the purpose of reducing the information amount of reception quality information transmitted on uplink (Patent Documents 1 and 2, and Non-patent Documents 3 and 4).
(1) A method where each communication terminal apparatus measures reception quality of all the channels that the base station apparatus allocates to each communication terminal apparatus for communications for each communication terminal apparatus, and notifies the base station apparatus of only an average value of the reception quality of all the channels (first measure).
(2) A method where each communication terminal apparatus selects the predetermined number of channels providing excellent reception quality in descending order of the reception quality from all the channels that the base station apparatus allocates to each communication terminal apparatus for communications, and notifies the base station apparatus of only the reception quality of the selected channels (second measure).
(3) A method where each communication terminal apparatus selects some reference channels from all the channels that the base station apparatus allocates to each communication terminal apparatus for communications, represents a value of reception quality of each channel using a difference value from the reception quality of the reference channel, and notifies the base station apparatus of the difference value (third measure).    Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-208234    Patent Document 2: Japanese Laid-Open Patent Publication No. 2006-50545    Non-patent Document 1: Kishiyama, et al. “Experimental Evaluations of Adaptive Modulation and Channel Coding in Forward Link for VSF-OFCDM Broadband Wireless Access”, IEICE Technical Report, 2003, May, RCS2003-25    Non-patent Document 2: Maehara, et al. “On OFDM/TDD Transmission Scheme with Subcarrier Adaptive Modulation”, IEICE General Conference, 2001, March, B-5-100, p. 498    Non-patent Document 3: “CQI report and scheduling procedure”, 3GPP, TSG-RAN WG1 Meeting #42bis, R1-051045, 2005, October    Non-patent Document 4: “Sensitivity of DL/UL Performance to CQI-Compression with Text Proposal”, 3GPP, TSG-RAN WG1 ad hoc meeting on LTE, R1-060228, 2006, January